Resumen

Johnson and Raye (1981) proposed a model of a process to differentiate between self-generated and perceptual memories, which is based on the distinctive qualities of representations of both memories. Descriptions of self-generated memories are usually longer and have more references to cognitive operations and, in general, more idiosyncratic information. These descriptions of self-generated memories, also, have less sensorial and contextual details than the descriptions of perceptual memories. These differences have been also found between real memory descriptions and those generated by misleading information (Schooler et al., 1986, 1988), lies (Alonso-Quecuty, 1992) or self-suggested information based on previous knowledge (Diges, 1992). On the other hand, it has been investigated how several factors influence the differential features of both types of memory descriptions. Suengas (1991) point out five variables with an influence in reality monitoring process: age, information subject matter, delay, thinking or talking about memory contents, perceptive resemblance and the cutting down in the cognitive mechanisms.The aim of this study was to examine the effect of preparation on the characteristics of imagined and perceptual memory descriptions. Following recentresearch (Alonso-Quecuty, 1992; Suengas and Johnson, 1988) it was hypothesized that real memories of subjects in the preparation condition would contain more sensorial and contextual details and more internal characteristics (in terms of the Johnson and Raye, 1981, reality monitoring) than subjects in the no-preparation condition. Also, descriptions of subjects asked to prepare a report of an imagined event should contain more external characteristics than the imagined memories of subjects who do not receive instructions about preparing their reports.A 2x2 factorial design was used, which included the between-subjects manipulation of two variables: the origin of the memory (perceived vs. imagined) and the preparation of reports (prepared vs. not-prepared). And, the free recall measures included: accuracy variables (sensorial and contextual details and distortions) and qualitative variables (explanations, length of the narrative, changes in the narrative order, reference to cognitive processes, dubitative expressions, impossible information and spontaneous corrections). Half of the subjects were asked to remember a filmed traffic accident (27 secs. duration). The rest of the subjects were presented with verbal description of the accident and were asked to imagine it. Half of each group were instructed to prepare the reports before give it them; the other half were not instructed to do this. Then, the reports were typed and analysed by two independent trained judges in terms of the presence or absence of the quantitative and qualitative variables. The scoring sys-tem used to analyse the statements was developed and validated in previous studies (e.g., Diges et al., 1990). Previous analysis showed that imagined and perceptual descriptions cannot be directly compared because of the imagined instructions. Thus, the preparation effects on perceptual and on imagined descriptions were analysed separately. On the external memories, the results showed that preparation significantly increased the number of sensorial and contextual details (t(28)=1.6l8; p<.05) and dubitative expressions (t(28)=2.687; p<.01). This effect of preparation could have been caused not only by the information organization determined by the preparation process, but also by a greater effort to recall involved in this process. These results are in agreement with the findings of Alonzo-Quecuty (1992) who observed that delayed reports had more sensorial and contextual information and more idiosyncratic features. Our results also coincided with the obtained by Suengas and Johnson (1988) who found that delay (associated to thinking and talking about the stored information) did not affect the contextual information but influence the idiosyncratic information contained in the reports of real events. This effect was observed mainly when subjective and affective connotations were the main characteristics of them.In summary, when the reports of previously experienced events are prepared, these reports exhibit more internal characteristics (idiosyncratic information) and more sensorial and contextual details than when they are not prepared.With respect to descriptions of memories for imagined events the results showed that the effects of preparation on the number of sensorial and contextual details (t(32)= 1.867; p<.05) and explanations (t(32)= 1.688; p<.05) were significant. Prepared reports of an imagined event had less idiosyncratic information, in the sense that they had less explanations than the non-prepared ones. And also, subjects under the prepared conditions recalled more details than in the non-prepared condition, as it happened in the real memory case. These results are also in agreement with Alonso-Quecuty's (1992) findings. She found that the delayed false declarations had less idiosyncratic information and more sensorial and contextual details than the immediate ones. Thus, preparation provoked internal narratives become more external.How could we explain this preparation effect on imagined and real memories? When presented with the real events subjects perceived, coded, and stored the selective information about the events. When subjects were asked to prepare their memory descriptions they retrieved the memory traces and reconstructed the information. When they talked about the event they spoke not about the perceived event but about the interpreted, coded, reorganised, stored, recalled and reconstructed event. This is the recall of a «trace» of memory (perhaps, it could be defined as a re-representation in terms of Johnson and Raye, 1981). As a result of this reconstructive process the memories of the external event acquire more internal characteristics because of a greater implication of cognitive pro-cesses. On the other hand, preparation produces an enrichment of the memories of the imagined events resulting in memory descriptions with more external characteristics (more sensorial and contextual details) and less internal ones. Here we have the recall about a memory trace of an internally experienced event.Finally, the significanes of these results for theoretical explanations about retrieval and discrimination processes is examined.